require.h

#ifndef REQUIRE_H
#define REQUIRE_H
#include <cstdio>
#include <cstdlib>
#include <fstream>
#include <string>

inline void require(bool requirement,
  const std::string& msg = "Requirement failed"){
  using namespace std;
  if (!requirement) {
    fputs(msg.c_str(), stderr);
    fputs("\n", stderr);
    exit(1);
  }
}

inline void requireArgs(int argc, int args,
  const std::string& msg =
    "Must use %d arguments") {
  using namespace std;
   if (argc != args + 1) {
     fprintf(stderr, msg.c_str(), args);
     fputs("\n", stderr);
     exit(1);
   }
}

inline void requireMinArgs(int argc, int minArgs,
  const std::string& msg =
    "Must use at least %d arguments") {
  using namespace std;
  if(argc < minArgs + 1) {
    fprintf(stderr, msg.c_str(), minArgs);
    fputs("\n", stderr);
    exit(1);
  }
}

inline void assure(std::ifstream& in,
  const std::string& filename = "") {
  using namespace std;
  if(!in) {
    fprintf(stderr, "Could not open file %s\n",
      filename.c_str());
    exit(1);
  }
}

inline void assure(std::ofstream& out,
  const std::string& filename = "") {
  using namespace std;
  if(!out) {
    fprintf(stderr, "Could not open file %s\n",
      filename.c_str());
    exit(1);
  }
}
#endif // REQUIRE_H